The immediate objective is to obtain and analyze biomedical data (on anthropology, demography, genetics, biochemistry, immunology, and disease) from two tribal groups in the British Solomons -- on Ontong Java, an isolated atoll, and on Ulawa, a small volcanic island of Malaita. The long-range objective is to study human ecology -- that is, to relate culture, habitat, and biology, including disease, in a spectrum of Solomon Island societies varying in genetic background, way of life, natural setting (atoll, coastal, mountain), and contact with Western civilization. Research on Ontong Java and Ulawa will complete the first phase of the long-term project. Since 1966, six Melanesian groups have been studied by teams of anthropologists and physicians: five tribes of inland cultivators on Bougainville and Malaita, and Malaitan fishermen living on artificial islets in a shallow, salt-water lagoon. The ecologic, cultural, and genetic diversity represented by the Ontong Javanese and Ulawans will fill out the spectrum, with a total now of eight tribes. This project, part of the International Biological Program, follows recommendations of the World Health Organization for multidisciplinary research on "primitive" peoples while they are still primitive. Findings can be applied to similar populations in the U.S. Pacific Trust Territory and to man-environment-disease problems in the U.S. Service to the Solomon Islanders and to their responsible administrators is an integral part of the project.